std::list::...ist::cbegin(3)

✨ std::list::begin, std::list::cbegin ✨

okay bestie so this is the page for std::list::begin and std::list::cbegin from the C++ Standard Libary (their spelling, not mine 💅), and it's literally the whole glow-up manual for getting an iterator pointed at the front of your list. it's giving "first day of school energy" fr fr 💖

---

🌸 Synopsis

iterator begin();                       (1) (noexcept since C++11)
const_iterator begin() const;           (2) (noexcept since C++11)
const_iterator cbegin() const noexcept; (3) (since C++11)

so what does it do? it returns an iterator to the first element of the list. that's it. that's the whole vibe. 🎀

and the tea ☕ — if the list is empty, the iterator you get back will be equal to end(). so like, no element, no problem, but also no element. 🙈

range-begin-end.svg — yes that's a file name that's just sitting there in the original, iconic honestly, I don't make the rules 🦋

---

✨ Parameters

none — she takes nothing, she needs nothing, she's that girl 💅

---

🫶 Return value

an iterator to the first element. periodt.

---

⭐ Complexity

Constant. O(1) baby, instant, zero waiting, ate and left no crumbs 🔥

---

📝 Notes

libc++ backports cbegin() to C++98 mode. yep, they really did that, little time-traveler behavior, so proud 😭💜

---

🌈 Example

#include <algorithm>
#include <iostream>
#include <numeric>
#include <string>
#include <list>

int main()
{
    std::list<int> nums{1, 2, 4, 8, 16};
    std::list<std::string> fruits{"orange", "apple", "raspberry"};
    std::list<char> empty;

    // Print list.
    std::for_each(nums.begin(), nums.end(), [](const int n) { std::cout << n << ' '; });
    std::cout << '\n';

    // Sums all integers in the list nums (if any), printing only the result.
    std::cout << "Sum of nums: "
              << std::accumulate(nums.begin(), nums.end(), 0) << '\n';

    // Prints the first fruit in the list fruits, checking if there is any.
    if (!fruits.empty())
        std::cout << "First fruit: " << *fruits.begin() << '\n';

    if (empty.begin() == empty.end())
        std::cout << "list 'empty' is indeed empty.\n";
}

ngl the original also had the comment // Run this code chilling above the #include block — main character energy, go hit run, I believe in you 🧚✨

💻 Output:

1 2 4 8 16
Sum of nums: 31
First fruit: orange
list 'empty' is indeed empty.

look at that. 1 2 4 8 16, sum is 31, first fruit is orange (correct answer, apple could never 🍊👑), and the empty list really did prove it's empty. slay.

---

👀 See also

• end — returns an iterator to the end
• cend — (public member function) (C++11)
• begin
• cbegin — returns an iterator to the beginning of a container or array, (function template) (C++11) (C++14)

---

💖 source: http://cppreference.com — version 2024.06.10 — and that's the whole page bestie, go forth and iterate from the beginning, ily, mwah 🫶🎀✨